Reply to the letter from Gazulla et al.

However, we completely agree with Dr Gazulla et al.'s assumption that PLS, like ALS, is not a pure motor neurone disease but rather a multisystem neurodegenerative disease defined by a predominant motor system injury. Moreover, Bede's team has demonstrated the existence of cerebellar atrophy in sporadic ALS and in ALS linked to I C9orf72 i abnormal G4C2 expansion [5,6]. We read with great interest the letter of Drs Gazulla and collaborators, who suggested that the continuum between primary lateral sclerosis (PLS) and amyotrophic lateral sclerosis (ALS) is not straightforward [1]. [Extracted from the article]